Although Apple's share of the enterprise market will remain small compared to rivals like Microsoft and Windows computer and tablet manufacturers -- the latter, for instance, will sell $69 billion in hardware to enterprises this year -- Apple's uptick is impressive.

More so, even, than the often-touted move by companies to cloud-based services, Bartels argued.

"The biggest disruptive force in the computer equipment market is not [the cloud], but Apple," Bartels said in a recent report. "Its rapid growth in the corporate market has been the big surprise of 2011, and it will be even more of a factor in 2012."

He attributed Apple's recent high corporate sales growth rate to what he called "clandestine" acquisitions of Macs by higher-level employees -- who are sometimes reimbursed by their firms -- iPad purchases by IT departments, and small businesses buying computers and tablets for both personal and business use.

"The Apple assault on the corporate market has so far taken place without much formal Apple support, and probably without Apple itself understanding its full extent," Bartels said.

While he stressed that his numbers were only estimates -- Apple does not break out sales to businesses in its earnings statements -- he defended them as "in the ballpark." More importantly, he was confident that Apple, at least in the mid-term, would be able to sustain those growth rates.

"Tim Cook is much more attuned to the corporate market than Steve Jobs was," said Bartels in an interview today, referring to Apple's current and former CEOs. Jobs, Bartels noted, was famously dismissive of the enterprise market. "But Cook could be a difference maker."

Cook, who was Apple's chief operating officer before taking the CEO spot last August, was the company's day-to-day leader during Jobs' last two years, when the iconic entrepreneur took a pair of months-long medical leaves.

Jobs died in October, less than two months after stepping down as CEO.

Bartels cited several moves Apple has made to accommodate enterprises, including creating a corporate sales team and offering volume discounts on iPads.

"I don't think they'll turn themselves inside out," said Bartels, to mimic Microsoft," but I do think that Apple will be more supportive of the corporate market as time goes on."

And if Apple does nothing more than it's already doing, Bartels was confident his estimates would stand up. "Even if Apple doesn't make tremendous changes, there are forces running in their favor, like 'take an Apple to work,'" Bartels said, referring to the trend of company workers bringing Macs or iPads they've bought themselves into the office.

In some companies, employees -- particularly upper-level executives -- are reimbursed for machines they buy on their own dime.

Bartels is not alone in noting the trend, which more broadly goes by the term "consumerization of IT."

But Apple has some potential hurdles before it in the enterprise.

While the company has profited from its early lead in both tablets and light-thin notebooks -- the former with the iPad, the latter with the MacBook Air line -- it will face competition from Windows-based ultrabooks and tablets, particularly after the release of Windows 8.

"That's one of the key questions," Bartels admitted. "Apple has been in a very good position with the iPad and MacBook Air, and they've given them a lot of advantages, but Microsoft [and OEMs] will come up with alternatives."

And when that happens, when ultrabooks -- and to a lesser extent, Windows 8 tablets -- become ubiquitous, Apple could lose its edge.

"Assuming Microsoft gets its act together, it will be a much more competitive landscape -- likely in 2013, not this year -- for tablets and ultrabooks," said Bartels. "If it turns out to be a three-way battle in tablets, with Apple, Google's Android, and Microsoft's Windows 8, for instance, IT departments will feel a lot more comfortable with Microsoft than with Android. Microsoft could quickly go to No. 2."